This invention relates to a router tool and cutting insert for the same for machining of a work piece, preferably of fiber reinforced plastics. The router tool is provided with cutting edges having teeth which mainly project in the rotational direction of the router. The tips of one cutting edge are staggered with respect to the tips of the other cutting edge. Each tooth has cutting portions the main directions of which converge in the rotational direction of the router.
It is previously known to use tools to machine composite materials. The problem when milling composite materials, such as plastics reinforced with polyaramide fibers, is that the fibers are difficult to cut at one or both of the major surfaces of the work piece as the very strong fibers therein are not supported against the arising cutting forces. One of the tools used is a type of milling cutter provided with right-hand and left-hand turned chip gullets, forming crosses on the milling cutter body. This milling cutter body demands a thorough positioning in the axial direction in order to be able to cut the composite material and also causes vibrations during the machining. The fibers being exposed form a fray on one or both sides of the place of machining, i.e. frayed edge. The fray may wind around the milling cutter and cause a clogging of melted plastics, and thus stopping the machining of the material. Furthermore the conventional milling cutters are expensive to fabricate and to regrind.
The present invention is provided to solve the above-mentioned drawbacks, wherein the afore-mentioned tips in one cutting edge are staggered with respect to the tips in the other cutting edge, so that the fibers at least at one instance during a revolution of the cutting tool have support for the arising cutting forces. Furthermore, a planar surface is achieved in the work piece due to the shape of the cutting edges.